Billiard ball rack



FIG. 1 is a top, front, and left side perspective view of a billiard ball rack showing my new design;

FIG. 2 is a front elevational view thereof, the undisclosed rear and right sides being identical in appearance;

FIG. 3 is a top plan view thereof; and,

FIG. 4 is a bottom plan view thereof. 

We claim the ornamental design for a billiard ball rack, as shown and described. 